The present invention relates to the general field of vaporizing apparatus, and particularly to steam-pressing irons in which it is necessary to assure the vaporization of a liquid before its expulsion in the form of steam.
The invention is particularly concerned with steam irons of the type having a pressing soleplate, heating means and a vaporization chamber provided with a coating which promotes the vaporization of the pressing liquid, which is generally water.
As is known in fields relating to the generation of steam, water droplets projected onto a hot surface tend to resist vaporization and to remain in the form of liquid droplets and to circulate rapidly and in a random manner across the surface. This phenomenon is known as calefaction.
It is already known in the art to improve the quality of the vaporization of water by applying to the bottom of the vaporization chamber of the iron a coating, such as of sodium silicate. This product, or other equivalent products, are known for their hydrophilic and wettability properties which assure a spreading and a distribution of the water across the bottom of the vaporization chamber. One thus obtains a better vaporization of the water, which translates into a reduction in the expulsion of water in liquid form through steam passages formed in the soleplate.
Experience has shown that the use of such coatings is not sufficient to assure an effective vaporization, in particular in modern pressing irons which are constructed to produce high steam outputs, for example equal to or greater than 30 grams per minute. Thus, coatings of the sodium silicate type have a resistance to thermal shocks which is less than totally desirable, and a limited adherence to the bottom of the vaporization chamber. There has also been noted a marked tendency for the materials employed for such coatings to dissolve in water, thereby significantly reducing the useful life of the pressing irons.
In addition, it is known in the prior art, as disclosed for example in German Laid-Open Application (DE-OS) A-3 006 783, to dispose a screen of metal wires directly on the bottom of a vaporization chamber.
The provision of such a screen, however, does not sufficiently limit the phenomenon of calefaction and the vaporization performance is thus found to be insufficient for use in an iron which must generate a substantial quantity of steam.
It has moreover also been noted that the manipulations performed on a pressing iron during ironing cause the body of water contained in the vaporization chamber to experience continuous movements. Such movements interfere with a good distribution of the water and have a negative influence on the quantity of steam generated.